udp: add low latency socket poll support

Add upport for busy-polling on UDP sockets.
In __udp[46]_lib_rcv add a call to sk_mark_ll() to copy the napi_id
from the skb into the sk.
This is done at the earliest possible moment, right after we identify
which socket this skb is for.
In __skb_recv_datagram When there is no data and the user
tries to read we busy poll.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b5808539cd5c..f77e34c5a0e2 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -46,6 +46,7 @@
 #include <net/ip6_checksum.h>
 #include <net/xfrm.h>
 #include <net/inet6_hashtables.h>
+#include <net/ll_poll.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -841,7 +842,10 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
          */
         sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
         if (sk != NULL) {
-                int ret = udpv6_queue_rcv_skb(sk, skb);
+                int ret;
+
+                sk_mark_ll(sk, skb);
+                ret = udpv6_queue_rcv_skb(sk, skb);
                 sock_put(sk);
 
                 /* a return value > 0 means to resubmit the input, but